1. Field of the Invention
The present invention relates in general to apparatus for use in subterranean wells that produce hydrocarbon fluids such as gas and oil and in particular to a side intake valve assembly that accepts water from a producing zone that has been separated from hydrocarbon fluids and enables the hydrocarbon fluid to be pumped to the surface and forces the water that is produced from the producing zone into a disposal zone downhole such that the water does not have to be pumped to the surface.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Hydrocarbon fluids are found in subterranean layers that are reached with wells drilled from the surface down through the layers of interest. The layers may contain hydrocarbon fluids such as gas and oil that are desired to be produced to the surface. They also produce water which, when having to be pumped to the surface, requires a great deal of energy that is wasted inasmuch as the water cannot be used.
The wells are encased with a heavy steel pipe that is usually cemented in place so that the fluids cannot escape or flow along the space between the casing and the borehole wall.
In the prior art, in some instances, the water produced is separated downhole in the casing from the hydrocarbon fluids. The mixture of the hydrocarbon fluids and water flows through perforations of the casing wall from a production zone into the interior thereof where the hydrocarbon fluid floats on top of the water inasmuch as it is lighter than the water. A water disposal zone may be located at a distance beneath the production zone. A pump may be installed downhole so that the separated water may be forced into the lower water disposal zone. Such a system is disclosed in U.S. Pat. No. 3,167,125. In that patent, there is formed a seal inside the casing between an upper production layer and a lower water disposal layer or area. The heavier unwanted water and the hydrocarbons stratify in the well casing. Thus the water that is separated from the hydrocarbon is pumped downwardly into the water disposal layer. A production tubing string extends downwardly through the well casing and the seal or packer, well known in the art, is placed between the production zone and the water disposal zone to separate the two zones in a fluid-tight relationship. The separated hydrocarbons are pumped to the surface through the production tubing string while the separated water in the production tubing string is forced downwardly below the packer and out into the water disposal zone.
In U.S. Pat. No. 5,176,216, a subterranean tool is disclosed in the form of a bypass tool and is positioned between a producing zone and a lower water disposal zone. The hydrocarbon in the form of a gas is produced upwardly through the annulus between the tubing and the casing and the salt water flows down through a longitudinal tube in a sleeve so that it can be disposed in the lower disposal zone.
In U.S. Pat. No. 5,497,832, a system is disclosed for improving the economics of production by reducing lifting costs of a producing well by utilizing the upstroke of a pump to produce a fluid mixture of primarily oil with only a fraction of the produced water and using the downstroke to inject the remaining produced water beneath a packer into a lower formation.
These prior art systems generally use spring-loaded valves wherein the springs assist in the opening and the closing of the valves. The environment in which these springs are used include high temperatures, corrosive well fluids, and great depths at which the valves operate. Such an environment creates problems that must be periodically addressed such as replacing the springs which requires the pulling of the production tubing string from the well casing, a very expensive and time-consuming process.
Further, some prior art valve systems are located on the outside of the production tubing string. This causes a greater outside diameter of the tubing string and thus a greater diameter well casing. Also, side forces on the tubing string can damage such side intake valve assembly.
It would be ideal to have a valve system mounted on the inside of the production tubing string instead of the outside to conserve downhole space and protect the valve from damage that can occur when it is mounted on the outside of the production tubing string. Further, such valve system should not require springs or other resilient mechanical devices to assist in opening and closing the valve.